Separation devices for separating a component from a multicomponent mixture are provided. The separation devices can include a body that defines a separation channel with a cross-sectional geometry that is not circular, rectangular, or square. The separation devices can be positioned relative to a base having an acoustic wave generator. A standing bulk acoustic wave generated by the acoustic wave generator can separate one or more components from the multicomponent mixture. Methods are provided for separating one or more components from a multicomponent mixture using the separation devices.